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Posted to user@cassandra.apache.org by Joaquin Casares <jo...@thelastpickle.com> on 2017/03/03 17:34:58 UTC
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since
batch statements will cause more work on the coordinator node while
individual requests, when using a TokenAwarePolicy, will hit a specific
coordinator, perform a local disk seek, and return the requested
information.
The only times that using batch statements are ideal is if writing to the
same partition key, even if it's across multiple tables when using the same
hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying
to accomplish and how many child statements were bundled up within that
batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com> wrote:
> Hello,
>
> More than 30 plus Cassandra servers in the primary DC went down OOM
> exception below. What puzzles me is the scale at which it happened (at the
> same minute). I will share some more details below.
>
> System Log: http://pastebin.com/iPeYrWVR
> GC Log: http://pastebin.com/CzNNGs0r
>
> <http://pastebin.com/CzNNGs0r>During the OOM I saw lot of WARNings like
> the below (these were there for quite sometime may be weeks)
> *WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209
> BatchStatement.java:252 - Batch of prepared statements for [keyspace.table]
> is of size 225455, exceeding specified threshold of 65536 by 159919.*
>
> * Environment:*
> We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more
> C* nodes on SSD and apps run here) and secondary DC (geographically remote
> and more like a DR to primary) on SAS drives.
> Cassandra config:
>
> Java 1.8.0_65
> Garbage Collector: G1GC
> memtable_allocation_type: offheap_objects
>
> Post this OOM I am seeing huge hints pile up on majority of the nodes and
> the pending hints keep going up. I have increased HintedHandoff
> CoreThreads to 6 but that did not help (I admit that I tried this on one
> node to try).
>
> nodetool compactionstats -H
> pending tasks: 3
> compaction type keyspace table
> completed total unit progress
> Compaction system hints
> 28.5 GB 92.38 GB bytes 30.85%
>
>
> Appreciate your inputs here.
>
> Thanks,
> Shravan
>
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by Jeff Jirsa <jj...@apache.org>.
On 2017-03-04 07:23 (-0800), "Thakrar, Jayesh" <jt...@conversantmedia.com> wrote:
> LCS does not rule out frequent updates - it just says that there will be more frequent compaction, which can potentially increase compaction activity (which again can be throttled as needed).
> But STCS will guarantee OOM when you have large datasets.
> Did you have a look at the offheap + onheap size of our jvm using "nodetool -info" ?
>
>
STCS does not guarantee you OOM when you have large datasets, unless by large datasets you mean in the tens-of-terabytes range, which is already something we typically recommend against.
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by Edward Capriolo <ed...@gmail.com>.
On Saturday, March 4, 2017, Thakrar, Jayesh <jt...@conversantmedia.com>
wrote:
> LCS does not rule out frequent updates - it just says that there will be
> more frequent compaction, which can potentially increase compaction
> activity (which again can be throttled as needed).
>
> But STCS will guarantee OOM when you have large datasets.
>
> Did you have a look at the offheap + onheap size of our jvm using
> "nodetool -info" ?
>
>
>
>
>
> *From: *Shravan C <challa17@outlook.com
> <javascript:_e(%7B%7D,'cvml','challa17@outlook.com');>>
> *Date: *Friday, March 3, 2017 at 11:11 PM
> *To: *Joaquin Casares <joaquin@thelastpickle.com
> <javascript:_e(%7B%7D,'cvml','joaquin@thelastpickle.com');>>, "
> user@cassandra.apache.org
> <javascript:_e(%7B%7D,'cvml','user@cassandra.apache.org');>" <
> user@cassandra.apache.org
> <javascript:_e(%7B%7D,'cvml','user@cassandra.apache.org');>>
> *Subject: *Re: OOM on Apache Cassandra on 30 Plus node at the same time
>
>
>
> We run C* at 32 GB and all servers have 96GB RAM. We use STCS . LCS is not
> an option for us as we have frequent updates.
>
>
>
> Thanks,
>
> Shravan
> ------------------------------
>
> *From:* Thakrar, Jayesh <jthakrar@conversantmedia.com
> <javascript:_e(%7B%7D,'cvml','jthakrar@conversantmedia.com');>>
> *Sent:* Friday, March 3, 2017 3:47:27 PM
> *To:* Joaquin Casares; user@cassandra.apache.org
> <javascript:_e(%7B%7D,'cvml','user@cassandra.apache.org');>
> *Subject:* Re: OOM on Apache Cassandra on 30 Plus node at the same time
>
>
>
> Had been fighting a similar battle, but am now over the hump for most part.
>
>
>
> Get info on the server config (e.g. memory, cpu, free memory (free -g),
> etc)
>
> Run "nodetool info" on the nodes to get heap and off-heap sizes
>
> Run "nodetool tablestats" or "nodetool tablestats <kespace>.<tablename>"
> on the key large tables
>
> Essentially the purpose is to see if you really had a true OOM or was your
> machine running out of memory.
>
>
>
> Cassandra can use offheap memory very well - so "nodetool info" will give
> you both heap and offheap.
>
>
>
> Also, what is the compaction strategy of your tables?
>
>
>
> Personally, I have found STCS to be awful at large scale - when you have
> sstables that are 100+ GB in size.
>
> See https://issues.apache.org/jira/browse/CASSANDRA-10821?
> focusedCommentId=15389451&page=com.atlassian.jira.
> plugin.system.issuetabpanels:comment-tabpanel#comment-15389451
>
>
>
> LCS seems better and should be the default (my opinion) unless you want
> DTCS
>
>
>
> A good description of all three compactions is here -
> http://docs.scylladb.com/kb/compaction/
>
> Documentation <http://docs.scylladb.com/kb/compaction/>
>
> docs.scylladb.com
>
> Scylla is a Cassandra-compatible NoSQL data store that can handle 1
> million transactions per second on a single server.
>
>
>
>
>
>
>
> *From: *Joaquin Casares <joaquin@thelastpickle.com
> <javascript:_e(%7B%7D,'cvml','joaquin@thelastpickle.com');>>
> *Date: *Friday, March 3, 2017 at 11:34 AM
> *To: *<user@cassandra.apache.org
> <javascript:_e(%7B%7D,'cvml','user@cassandra.apache.org');>>
> *Subject: *Re: OOM on Apache Cassandra on 30 Plus node at the same time
>
>
>
> Hello Shravan,
>
>
>
> Typically asynchronous requests are recommended over batch statements
> since batch statements will cause more work on the coordinator node while
> individual requests, when using a TokenAwarePolicy, will hit a specific
> coordinator, perform a local disk seek, and return the requested
> information.
>
>
>
> The only times that using batch statements are ideal is if writing to the
> same partition key, even if it's across multiple tables when using the same
> hashing algorithm (like murmur3).
>
>
>
> Could you provide a bit of insight into what the batch statement was
> trying to accomplish and how many child statements were bundled up within
> that batch?
>
>
>
> Cheers,
>
>
>
> Joaquin
>
>
> Joaquin Casares
>
> Consultant
>
> Austin, TX
>
>
>
> Apache Cassandra Consulting
>
> http://www.thelastpickle.com
>
> The Last Pickle • Apache Cassandra Consulting & Services
> <http://www.thelastpickle.com/>
>
> www.thelastpickle.com
>
> Apache Cassandra Consulting & Services. Our wealth of experience with
> Apache Cassandra will ensure success at all stages of a your project
> lifecycle.
>
>
>
> On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <challa17@outlook.com
> <javascript:_e(%7B%7D,'cvml','challa17@outlook.com');>> wrote:
>
> Hello,
>
> More than 30 plus Cassandra servers in the primary DC went down OOM
> exception below. What puzzles me is the scale at which it happened (at the
> same minute). I will share some more details below.
>
> System Log: http://pastebin.com/iPeYrWVR
>
> GC Log: http://pastebin.com/CzNNGs0r
>
> During the OOM I saw lot of WARNings like the below (these were there for
> quite sometime may be weeks)
> *WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209
> BatchStatement.java:252 - Batch of prepared statements for [keyspace.table]
> is of size 225455, exceeding specified threshold of 65536 by 159919.*
>
> * Environment:*
> We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more
> C* nodes on SSD and apps run here) and secondary DC (geographically remote
> and more like a DR to primary) on SAS drives.
> Cassandra config:
>
> Java 1.8.0_65
> Garbage Collector: G1GC
> memtable_allocation_type: offheap_objects
>
> Post this OOM I am seeing huge hints pile up on majority of the nodes and
> the pending hints keep going up. I have increased HintedHandoff CoreThreads
> to 6 but that did not help (I admit that I tried this on one node to try).
>
> nodetool compactionstats -H
> pending tasks: 3
> compaction type keyspace table
> completed total unit progress
> Compaction system hints
> 28.5 GB 92.38 GB bytes 30.85%
>
>
>
> Appreciate your inputs here.
>
> Thanks,
>
> Shravan
>
>
>
>
Stcs does not guarentee oom with large sets. Cassandra had large sets for
yeara when stcs was the only thing that existed.
--
Sorry this was sent from mobile. Will do less grammar and spell check than
usual.
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by "Thakrar, Jayesh" <jt...@conversantmedia.com>.
If possible, I would suggest running that command on a periodic basis (cron or whatever).
Also, you can run it on a single server and iterate through all the nodes in the cluster/DC.
Would also recommend running "nodetool compactionstats
And looked at your concern about high value for hinted handoff.
That's good (in a way), it ensures that updates are not lost.
Its possible because your DB was constantly being updated and the servers that come up started accumulating for the servers that were still down.
Furthermore, that may have been the situation also as the servers were going down.
Hence high hinted handoff is just a sign of pending updates that need to be applied, which is not uncommon if you had servers falling down/restarting like dominos and updates still coming in.
From: Shravan C <ch...@outlook.com>
Date: Saturday, March 4, 2017 at 11:15 AM
To: Conversant <jt...@conversantmedia.com>, Joaquin Casares <jo...@thelastpickle.com>, "user@cassandra.apache.org" <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
I was looking at nodetool info across all nodes. Consistently JVM heap used is ~ 12GB and off heap is ~ 4-5GB.
________________________________
From: Thakrar, Jayesh <jt...@conversantmedia.com>
Sent: Saturday, March 4, 2017 9:23:01 AM
To: Shravan C; Joaquin Casares; user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
LCS does not rule out frequent updates - it just says that there will be more frequent compaction, which can potentially increase compaction activity (which again can be throttled as needed).
But STCS will guarantee OOM when you have large datasets.
Did you have a look at the offheap + onheap size of our jvm using "nodetool -info" ?
From: Shravan C <ch...@outlook.com>
Date: Friday, March 3, 2017 at 11:11 PM
To: Joaquin Casares <jo...@thelastpickle.com>, "user@cassandra.apache.org" <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
We run C* at 32 GB and all servers have 96GB RAM. We use STCS . LCS is not an option for us as we have frequent updates.
Thanks,
Shravan
________________________________
From: Thakrar, Jayesh <jt...@conversantmedia.com>
Sent: Friday, March 3, 2017 3:47:27 PM
To: Joaquin Casares; user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Had been fighting a similar battle, but am now over the hump for most part.
Get info on the server config (e.g. memory, cpu, free memory (free -g), etc)
Run "nodetool info" on the nodes to get heap and off-heap sizes
Run "nodetool tablestats" or "nodetool tablestats <kespace>.<tablename>" on the key large tables
Essentially the purpose is to see if you really had a true OOM or was your machine running out of memory.
Cassandra can use offheap memory very well - so "nodetool info" will give you both heap and offheap.
Also, what is the compaction strategy of your tables?
Personally, I have found STCS to be awful at large scale - when you have sstables that are 100+ GB in size.
See https://issues.apache.org/jira/browse/CASSANDRA-10821?focusedCommentId=15389451&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15389451
LCS seems better and should be the default (my opinion) unless you want DTCS
A good description of all three compactions is here - http://docs.scylladb.com/kb/compaction/
Documentation<http://docs.scylladb.com/kb/compaction/>
docs.scylladb.com
Scylla is a Cassandra-compatible NoSQL data store that can handle 1 million transactions per second on a single server.
From: Joaquin Casares <jo...@thelastpickle.com>
Date: Friday, March 3, 2017 at 11:34 AM
To: <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since batch statements will cause more work on the coordinator node while individual requests, when using a TokenAwarePolicy, will hit a specific coordinator, perform a local disk seek, and return the requested information.
The only times that using batch statements are ideal is if writing to the same partition key, even if it's across multiple tables when using the same hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying to accomplish and how many child statements were bundled up within that batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
The Last Pickle • Apache Cassandra Consulting & Services<http://www.thelastpickle.com/>
www.thelastpickle.com
Apache Cassandra Consulting & Services. Our wealth of experience with Apache Cassandra will ensure success at all stages of a your project lifecycle.
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com>> wrote:
Hello,
More than 30 plus Cassandra servers in the primary DC went down OOM exception below. What puzzles me is the scale at which it happened (at the same minute). I will share some more details below.
System Log: http://pastebin.com/iPeYrWVR
GC Log: http://pastebin.com/CzNNGs0r
During the OOM I saw lot of WARNings like the below (these were there for quite sometime may be weeks)
WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209 BatchStatement.java:252 - Batch of prepared statements for [keyspace.table] is of size 225455, exceeding specified threshold of 65536 by 159919.
Environment:
We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more C* nodes on SSD and apps run here) and secondary DC (geographically remote and more like a DR to primary) on SAS drives.
Cassandra config:
Java 1.8.0_65
Garbage Collector: G1GC
memtable_allocation_type: offheap_objects
Post this OOM I am seeing huge hints pile up on majority of the nodes and the pending hints keep going up. I have increased HintedHandoff CoreThreads to 6 but that did not help (I admit that I tried this on one node to try).
nodetool compactionstats -H
pending tasks: 3
compaction type keyspace table completed total unit progress
Compaction system hints 28.5 GB 92.38 GB bytes 30.85%
Appreciate your inputs here.
Thanks,
Shravan
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by Shravan C <ch...@outlook.com>.
I was looking at nodetool info across all nodes. Consistently JVM heap used is ~ 12GB and off heap is ~ 4-5GB.
________________________________
From: Thakrar, Jayesh <jt...@conversantmedia.com>
Sent: Saturday, March 4, 2017 9:23:01 AM
To: Shravan C; Joaquin Casares; user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
LCS does not rule out frequent updates - it just says that there will be more frequent compaction, which can potentially increase compaction activity (which again can be throttled as needed).
But STCS will guarantee OOM when you have large datasets.
Did you have a look at the offheap + onheap size of our jvm using "nodetool -info" ?
From: Shravan C <ch...@outlook.com>
Date: Friday, March 3, 2017 at 11:11 PM
To: Joaquin Casares <jo...@thelastpickle.com>, "user@cassandra.apache.org" <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
We run C* at 32 GB and all servers have 96GB RAM. We use STCS . LCS is not an option for us as we have frequent updates.
Thanks,
Shravan
________________________________
From: Thakrar, Jayesh <jt...@conversantmedia.com>
Sent: Friday, March 3, 2017 3:47:27 PM
To: Joaquin Casares; user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Had been fighting a similar battle, but am now over the hump for most part.
Get info on the server config (e.g. memory, cpu, free memory (free -g), etc)
Run "nodetool info" on the nodes to get heap and off-heap sizes
Run "nodetool tablestats" or "nodetool tablestats <kespace>.<tablename>" on the key large tables
Essentially the purpose is to see if you really had a true OOM or was your machine running out of memory.
Cassandra can use offheap memory very well - so "nodetool info" will give you both heap and offheap.
Also, what is the compaction strategy of your tables?
Personally, I have found STCS to be awful at large scale - when you have sstables that are 100+ GB in size.
See https://issues.apache.org/jira/browse/CASSANDRA-10821?focusedCommentId=15389451&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15389451
LCS seems better and should be the default (my opinion) unless you want DTCS
A good description of all three compactions is here - http://docs.scylladb.com/kb/compaction/
Documentation<http://docs.scylladb.com/kb/compaction/>
docs.scylladb.com
Scylla is a Cassandra-compatible NoSQL data store that can handle 1 million transactions per second on a single server.
From: Joaquin Casares <jo...@thelastpickle.com>
Date: Friday, March 3, 2017 at 11:34 AM
To: <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since batch statements will cause more work on the coordinator node while individual requests, when using a TokenAwarePolicy, will hit a specific coordinator, perform a local disk seek, and return the requested information.
The only times that using batch statements are ideal is if writing to the same partition key, even if it's across multiple tables when using the same hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying to accomplish and how many child statements were bundled up within that batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
The Last Pickle • Apache Cassandra Consulting & Services<http://www.thelastpickle.com/>
www.thelastpickle.com
Apache Cassandra Consulting & Services. Our wealth of experience with Apache Cassandra will ensure success at all stages of a your project lifecycle.
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com>> wrote:
Hello,
More than 30 plus Cassandra servers in the primary DC went down OOM exception below. What puzzles me is the scale at which it happened (at the same minute). I will share some more details below.
System Log: http://pastebin.com/iPeYrWVR
GC Log: http://pastebin.com/CzNNGs0r
During the OOM I saw lot of WARNings like the below (these were there for quite sometime may be weeks)
WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209 BatchStatement.java:252 - Batch of prepared statements for [keyspace.table] is of size 225455, exceeding specified threshold of 65536 by 159919.
Environment:
We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more C* nodes on SSD and apps run here) and secondary DC (geographically remote and more like a DR to primary) on SAS drives.
Cassandra config:
Java 1.8.0_65
Garbage Collector: G1GC
memtable_allocation_type: offheap_objects
Post this OOM I am seeing huge hints pile up on majority of the nodes and the pending hints keep going up. I have increased HintedHandoff CoreThreads to 6 but that did not help (I admit that I tried this on one node to try).
nodetool compactionstats -H
pending tasks: 3
compaction type keyspace table completed total unit progress
Compaction system hints 28.5 GB 92.38 GB bytes 30.85%
Appreciate your inputs here.
Thanks,
Shravan
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by "Thakrar, Jayesh" <jt...@conversantmedia.com>.
LCS does not rule out frequent updates - it just says that there will be more frequent compaction, which can potentially increase compaction activity (which again can be throttled as needed).
But STCS will guarantee OOM when you have large datasets.
Did you have a look at the offheap + onheap size of our jvm using "nodetool -info" ?
From: Shravan C <ch...@outlook.com>
Date: Friday, March 3, 2017 at 11:11 PM
To: Joaquin Casares <jo...@thelastpickle.com>, "user@cassandra.apache.org" <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
We run C* at 32 GB and all servers have 96GB RAM. We use STCS . LCS is not an option for us as we have frequent updates.
Thanks,
Shravan
________________________________
From: Thakrar, Jayesh <jt...@conversantmedia.com>
Sent: Friday, March 3, 2017 3:47:27 PM
To: Joaquin Casares; user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Had been fighting a similar battle, but am now over the hump for most part.
Get info on the server config (e.g. memory, cpu, free memory (free -g), etc)
Run "nodetool info" on the nodes to get heap and off-heap sizes
Run "nodetool tablestats" or "nodetool tablestats <kespace>.<tablename>" on the key large tables
Essentially the purpose is to see if you really had a true OOM or was your machine running out of memory.
Cassandra can use offheap memory very well - so "nodetool info" will give you both heap and offheap.
Also, what is the compaction strategy of your tables?
Personally, I have found STCS to be awful at large scale - when you have sstables that are 100+ GB in size.
See https://issues.apache.org/jira/browse/CASSANDRA-10821?focusedCommentId=15389451&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15389451
LCS seems better and should be the default (my opinion) unless you want DTCS
A good description of all three compactions is here - http://docs.scylladb.com/kb/compaction/
Documentation<http://docs.scylladb.com/kb/compaction/>
docs.scylladb.com
Scylla is a Cassandra-compatible NoSQL data store that can handle 1 million transactions per second on a single server.
From: Joaquin Casares <jo...@thelastpickle.com>
Date: Friday, March 3, 2017 at 11:34 AM
To: <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since batch statements will cause more work on the coordinator node while individual requests, when using a TokenAwarePolicy, will hit a specific coordinator, perform a local disk seek, and return the requested information.
The only times that using batch statements are ideal is if writing to the same partition key, even if it's across multiple tables when using the same hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying to accomplish and how many child statements were bundled up within that batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
The Last Pickle • Apache Cassandra Consulting & Services<http://www.thelastpickle.com/>
www.thelastpickle.com
Apache Cassandra Consulting & Services. Our wealth of experience with Apache Cassandra will ensure success at all stages of a your project lifecycle.
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com>> wrote:
Hello,
More than 30 plus Cassandra servers in the primary DC went down OOM exception below. What puzzles me is the scale at which it happened (at the same minute). I will share some more details below.
System Log: http://pastebin.com/iPeYrWVR
GC Log: http://pastebin.com/CzNNGs0r
During the OOM I saw lot of WARNings like the below (these were there for quite sometime may be weeks)
WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209 BatchStatement.java:252 - Batch of prepared statements for [keyspace.table] is of size 225455, exceeding specified threshold of 65536 by 159919.
Environment:
We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more C* nodes on SSD and apps run here) and secondary DC (geographically remote and more like a DR to primary) on SAS drives.
Cassandra config:
Java 1.8.0_65
Garbage Collector: G1GC
memtable_allocation_type: offheap_objects
Post this OOM I am seeing huge hints pile up on majority of the nodes and the pending hints keep going up. I have increased HintedHandoff CoreThreads to 6 but that did not help (I admit that I tried this on one node to try).
nodetool compactionstats -H
pending tasks: 3
compaction type keyspace table completed total unit progress
Compaction system hints 28.5 GB 92.38 GB bytes 30.85%
Appreciate your inputs here.
Thanks,
Shravan
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by Shravan C <ch...@outlook.com>.
We run C* at 32 GB and all servers have 96GB RAM. We use STCS . LCS is not an option for us as we have frequent updates.
Thanks,
Shravan
________________________________
From: Thakrar, Jayesh <jt...@conversantmedia.com>
Sent: Friday, March 3, 2017 3:47:27 PM
To: Joaquin Casares; user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Had been fighting a similar battle, but am now over the hump for most part.
Get info on the server config (e.g. memory, cpu, free memory (free -g), etc)
Run "nodetool info" on the nodes to get heap and off-heap sizes
Run "nodetool tablestats" or "nodetool tablestats <kespace>.<tablename>" on the key large tables
Essentially the purpose is to see if you really had a true OOM or was your machine running out of memory.
Cassandra can use offheap memory very well - so "nodetool info" will give you both heap and offheap.
Also, what is the compaction strategy of your tables?
Personally, I have found STCS to be awful at large scale - when you have sstables that are 100+ GB in size.
See https://issues.apache.org/jira/browse/CASSANDRA-10821?focusedCommentId=15389451&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15389451
LCS seems better and should be the default (my opinion) unless you want DTCS
A good description of all three compactions is here - http://docs.scylladb.com/kb/compaction/
Documentation<http://docs.scylladb.com/kb/compaction/>
docs.scylladb.com
Scylla is a Cassandra-compatible NoSQL data store that can handle 1 million transactions per second on a single server.
From: Joaquin Casares <jo...@thelastpickle.com>
Date: Friday, March 3, 2017 at 11:34 AM
To: <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since batch statements will cause more work on the coordinator node while individual requests, when using a TokenAwarePolicy, will hit a specific coordinator, perform a local disk seek, and return the requested information.
The only times that using batch statements are ideal is if writing to the same partition key, even if it's across multiple tables when using the same hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying to accomplish and how many child statements were bundled up within that batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
The Last Pickle • Apache Cassandra Consulting & Services<http://www.thelastpickle.com/>
www.thelastpickle.com
Apache Cassandra Consulting & Services. Our wealth of experience with Apache Cassandra will ensure success at all stages of a your project lifecycle.
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com>> wrote:
Hello,
More than 30 plus Cassandra servers in the primary DC went down OOM exception below. What puzzles me is the scale at which it happened (at the same minute). I will share some more details below.
System Log: http://pastebin.com/iPeYrWVR
GC Log: http://pastebin.com/CzNNGs0r
During the OOM I saw lot of WARNings like the below (these were there for quite sometime may be weeks)
WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209 BatchStatement.java:252 - Batch of prepared statements for [keyspace.table] is of size 225455, exceeding specified threshold of 65536 by 159919.
Environment:
We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more C* nodes on SSD and apps run here) and secondary DC (geographically remote and more like a DR to primary) on SAS drives.
Cassandra config:
Java 1.8.0_65
Garbage Collector: G1GC
memtable_allocation_type: offheap_objects
Post this OOM I am seeing huge hints pile up on majority of the nodes and the pending hints keep going up. I have increased HintedHandoff CoreThreads to 6 but that did not help (I admit that I tried this on one node to try).
nodetool compactionstats -H
pending tasks: 3
compaction type keyspace table completed total unit progress
Compaction system hints 28.5 GB 92.38 GB bytes 30.85%
Appreciate your inputs here.
Thanks,
Shravan
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by "Thakrar, Jayesh" <jt...@conversantmedia.com>.
Had been fighting a similar battle, but am now over the hump for most part.
Get info on the server config (e.g. memory, cpu, free memory (free -g), etc)
Run "nodetool info" on the nodes to get heap and off-heap sizes
Run "nodetool tablestats" or "nodetool tablestats <kespace>.<tablename>" on the key large tables
Essentially the purpose is to see if you really had a true OOM or was your machine running out of memory.
Cassandra can use offheap memory very well - so "nodetool info" will give you both heap and offheap.
Also, what is the compaction strategy of your tables?
Personally, I have found STCS to be awful at large scale - when you have sstables that are 100+ GB in size.
See https://issues.apache.org/jira/browse/CASSANDRA-10821?focusedCommentId=15389451&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15389451
LCS seems better and should be the default (my opinion) unless you want DTCS
A good description of all three compactions is here - http://docs.scylladb.com/kb/compaction/
From: Joaquin Casares <jo...@thelastpickle.com>
Date: Friday, March 3, 2017 at 11:34 AM
To: <us...@cassandra.apache.org>
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since batch statements will cause more work on the coordinator node while individual requests, when using a TokenAwarePolicy, will hit a specific coordinator, perform a local disk seek, and return the requested information.
The only times that using batch statements are ideal is if writing to the same partition key, even if it's across multiple tables when using the same hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying to accomplish and how many child statements were bundled up within that batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com>> wrote:
Hello,
More than 30 plus Cassandra servers in the primary DC went down OOM exception below. What puzzles me is the scale at which it happened (at the same minute). I will share some more details below.
System Log: http://pastebin.com/iPeYrWVR
GC Log: http://pastebin.com/CzNNGs0r
During the OOM I saw lot of WARNings like the below (these were there for quite sometime may be weeks)
WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209 BatchStatement.java:252 - Batch of prepared statements for [keyspace.table] is of size 225455, exceeding specified threshold of 65536 by 159919.
Environment:
We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more C* nodes on SSD and apps run here) and secondary DC (geographically remote and more like a DR to primary) on SAS drives.
Cassandra config:
Java 1.8.0_65
Garbage Collector: G1GC
memtable_allocation_type: offheap_objects
Post this OOM I am seeing huge hints pile up on majority of the nodes and the pending hints keep going up. I have increased HintedHandoff CoreThreads to 6 but that did not help (I admit that I tried this on one node to try).
nodetool compactionstats -H
pending tasks: 3
compaction type keyspace table completed total unit progress
Compaction system hints 28.5 GB 92.38 GB bytes 30.85%
Appreciate your inputs here.
Thanks,
Shravan
Re: OOM on Apache Cassandra on 30 Plus node at the same time
Posted by Shravan C <ch...@outlook.com>.
Hi Joaquin,
We have inserts going into a tracking table. Tracking table is a simple table [PRIMARY KEY (comid, status_timestamp) ] with a few tracking attributes and sorted by status_timestamp. From a volume perspective it is not a whole lot.
Thanks,
Shravan
________________________________
From: Joaquin Casares <jo...@thelastpickle.com>
Sent: Friday, March 3, 2017 11:34:58 AM
To: user@cassandra.apache.org
Subject: Re: OOM on Apache Cassandra on 30 Plus node at the same time
Hello Shravan,
Typically asynchronous requests are recommended over batch statements since batch statements will cause more work on the coordinator node while individual requests, when using a TokenAwarePolicy, will hit a specific coordinator, perform a local disk seek, and return the requested information.
The only times that using batch statements are ideal is if writing to the same partition key, even if it's across multiple tables when using the same hashing algorithm (like murmur3).
Could you provide a bit of insight into what the batch statement was trying to accomplish and how many child statements were bundled up within that batch?
Cheers,
Joaquin
Joaquin Casares
Consultant
Austin, TX
Apache Cassandra Consulting
http://www.thelastpickle.com
On Fri, Mar 3, 2017 at 11:18 AM, Shravan Ch <ch...@outlook.com>> wrote:
Hello,
More than 30 plus Cassandra servers in the primary DC went down OOM exception below. What puzzles me is the scale at which it happened (at the same minute). I will share some more details below.
System Log: http://pastebin.com/iPeYrWVR
GC Log: http://pastebin.com/CzNNGs0r
<http://pastebin.com/CzNNGs0r>During the OOM I saw lot of WARNings like the below (these were there for quite sometime may be weeks)
WARN [SharedPool-Worker-81] 2017-03-01 19:55:41,209 BatchStatement.java:252 - Batch of prepared statements for [keyspace.table] is of size 225455, exceeding specified threshold of 65536 by 159919.
Environment:
We are using ApacheCassandra-2.1.9 on Multi DC cluster. Primary DC (more C* nodes on SSD and apps run here) and secondary DC (geographically remote and more like a DR to primary) on SAS drives.
Cassandra config:
Java 1.8.0_65
Garbage Collector: G1GC
memtable_allocation_type: offheap_objects
Post this OOM I am seeing huge hints pile up on majority of the nodes and the pending hints keep going up. I have increased HintedHandoff CoreThreads to 6 but that did not help (I admit that I tried this on one node to try).
nodetool compactionstats -H
pending tasks: 3
compaction type keyspace table completed total unit progress
Compaction system hints 28.5 GB 92.38 GB bytes 30.85%
Appreciate your inputs here.
Thanks,
Shravan